Design of a Portable Susceptometer with No Electromagnets

Magnetic materials characterization usually requires heavy equipment based on electromagnets, which limits their use to the laboratory. The volume of the typical samples is small in order to keep a good uniformity of the applied magnetic field in the sample. This kind of equipment is not appropriate for geological measurements in the field, where portable systems are required and samples have typically a higher volume. Here, we study the limits and applicability of a portable susceptometer device based on strong magnets potentially applicable in geological prospections. A new prototype has been built and tested. The device makes use of Nd–Fe–B magnets and an iron magnetic circuit (MC) to apply the magnetic field to the sample. A quasi-spherical geometry of the MC provides good uniformity of the magnetic field while keeping a moderate measuring volume. The equipment is powered by a 12-V battery and a mechanical design allows the control of the magnetic flux density in the range of approximately 30–130 mT.